The increasing use of solid state devices and solid state circuitry in electronic devices such as pocket calculators, digital electronic watches, small meters and similar products has given rise to a need for an extremely small electrical connector for forming connections between small parallel substrates such as the circuit board and the L.E.D. (light emitting diode) or liquid crystal unit of a watch. It is possible to obtain an insight into the dimensional requirements which must be met if one contemplates the dimensions of an ordinary wrist watch and reflects that the connector must fit between two parallel planes in the watch casing (the L.E.D. and the circuit board or substrate) and that as many as fifteen or twenty aligned terminal pads on the circuit substrate must be connected to a like number of terminal areas on the L.E.D. Conventional connector technology for making such substrate-to-substrate connections does not provide practical solutions to the problem. When the substrates are of the size of a printed circuit board of a few years ago, a conventional edge connector can simply be assembled to each board or substrate with wires extending between the sheet metal contact terminals in the housings of the connectors but it is impractical to scale down a conventional edge connector having a plastic housing and sheet metal terminals therein to the extent that two such connectors each having fifteen or so terminals therein could be fitted in the housing of an ordinary wrist watch.
The instant invention is accordingly directed to the problem of providing an extremely small connector which can, in the space available between two substrates contained in a wrist watch, function to electrically connect a substantial number of conductors on the opposed surfaces of the substrates. The invention is further directed to the provision of a connector having these capabilities and lying within the dimensional limitations discussed above which can, as a practical matter, be manufactured at a relatively low cost by a relatively simple and reliable assembly process.
It is accordingly an object of the invention to provide an improved subminiature electrical connector. A further object is to provide a subminiature electrical connector which can be manufactured at a low cost and which will serve reliably for an extended time period in subminiature circuit devices. A further object is to provide a versatile connector which can be used in a wide variety of extremely small electronic devices so that a standard connecting device can be used under many circumstances for different specific applications.